WO2009125788A1 - Electrically conductive film wherein carbon nanotubes are used, and method of producing same - Google Patents

Electrically conductive film wherein carbon nanotubes are used, and method of producing same Download PDF

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Publication number
WO2009125788A1
WO2009125788A1 PCT/JP2009/057184 JP2009057184W WO2009125788A1 WO 2009125788 A1 WO2009125788 A1 WO 2009125788A1 JP 2009057184 W JP2009057184 W JP 2009057184W WO 2009125788 A1 WO2009125788 A1 WO 2009125788A1
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carbon nanotubes
walled carbon
acid
conductive film
carbon nanotube
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PCT/JP2009/057184
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French (fr)
Japanese (ja)
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北野高広
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株式会社クラレ
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/04—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of carbon-silicon compounds, carbon or silicon

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  • the present invention relates to a transparent conductive film for use in a transparent electrode or the like and a method for producing the same. More specifically, the present invention relates to a conductive film using single-walled carbon nanotubes that have been acid-treated, alkali-treated, and acid-treated, and a method for producing the same.
  • a transparent conductive film made of single-walled carbon nanotubes purified by a wet method has a problem in that the conductivity decreases when left for a long time at a high temperature.
  • a method in which a sulfonic acid group-containing resin is provided as a protective layer and a method in which a functional group of a carbon nanotube is a carboxylic acid metal salt Patent Documents 2 and 3.
  • the method (patent documents 4, 5) which provides a protective layer is disclosed.
  • the method of providing the protective layer is an effective measure, and although heat resistance is improved as compared with the case without the protective layer, sufficient performance has not been obtained.
  • JP 2002-515847 A Japanese Patent Application No. 2007-089178 Japanese Patent Application No. 2007-089179 JP 2004-202948 A JP 2005-255985 A
  • an object of the present invention is to provide a conductive film composed of single-walled carbon nanotubes having high heat resistance and a method for producing a carbon nanotube dispersion for producing the conductive film.
  • the present inventors have found that the functional group imparted to the carbon nanotubes is effective in improving heat resistance if it is not a salt. I found out that there is.
  • a conductive film having high heat resistance can be obtained by using single-walled carbon nanotubes that have been acid-treated, alkali-treated, and further acid-treated, and as a result of further studies, conductive that can solve the above problems. The film was completed.
  • the present invention is a conductive film containing single-walled carbon nanotubes, wherein the single-walled carbon nanotubes are obtained by acid treatment, alkali treatment, and further acid treatment.
  • the conductive film preferably contains fullerene or an analog thereof.
  • the present invention is an electrode comprising the conductive film and a protective layer on a substrate.
  • the present invention also relates to a method for producing a single-walled carbon nanotube dispersion, wherein step 1: a step of obtaining a crude carbon nanotube, step 2: a step of acid-treating the crude carbon nanotube, step 3: a single-layer obtained in step 2 A step of alkali-treating carbon nanotubes, step 4: a step of filtering single-walled carbon nanotubes obtained in step 3, and step 5: a step of acid-treating single-walled carbon nanotubes obtained in step 4 A method for producing a conductive film, characterized by using a method for producing a single-walled carbon nanotube dispersion and a carbon nanotube dispersion obtained by the production method.
  • the present invention also relates to a method for producing a conductive film containing single-walled carbon nanotubes, which is obtained in Step 1: Step of obtaining crude carbon nanotubes; Step 2: Step of treating crude carbon nanotubes with acid; Step 3: Step 2. Obtained in step A; a step of obtaining a dispersion containing single-walled carbon nanotubes; and a step of filtering the single-walled carbon nanotubes obtained in step 3; A conductive film containing single-walled carbon nanotubes, comprising: a step B of applying a single-walled carbon nanotube on a substrate to obtain a conductive layer; and a step C of acid-treating the conductive layer obtained in step B. It is a manufacturing method.
  • the transparent conductive film made of single-walled carbon nanotubes according to the present invention has high-temperature durability and can be advantageously used as an electrode member for various displays such as liquid crystal screens and touch panels.
  • a single-walled carbon nanotube obtained by an arc discharge method which is an inexpensive raw material, can be used, and an acid treatment method that can be purified on an industrial scale can be used. Can be supplied stably.
  • the present invention is a conductive film containing single-walled carbon nanotubes, wherein the single-walled carbon nanotubes are acid-treated, alkali-treated, and further acid-treated.
  • the single-walled carbon nanotube used in the present invention is not particularly limited as long as it is a single-walled carbon nanotube obtained by a known production method, and any production method such as an arc discharge method, a chemical vapor deposition method, or a laser evaporation method can be used.
  • the production method by the arc discharge method is most preferable from the viewpoint of availability and crystallinity.
  • acid treatment is a general term for a method of immersing single-walled carbon nanotubes in an acidic liquid.
  • the acidic liquid is not particularly limited as long as it is a known compound, and specific examples include nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, and mixtures thereof.
  • the acid treatment prior to the alkali treatment is preferably acid treatment using nitric acid or a mixed solution of nitric acid and sulfuric acid, more preferably 80 to 100 ° C., more preferably 1 to 7 days. More preferred.
  • the amorphous carbon is decomposed to separate them, or the metal catalyst fine particles used when producing the single-walled carbon nanotubes It is a process necessary for disassembling.
  • the alkali treatment is a general term for a method of immersing single-walled carbon nanotubes in an alkaline liquid.
  • the alkaline liquid is not particularly limited as long as it is a known one, and specific examples include an aqueous lithium hydroxide solution, an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution, an aqueous ammonia solution, and an alkylamine aqueous solution such as propylamine and butylamine.
  • the alkaline liquid used during the alkali treatment is preferably a lithium hydroxide aqueous solution, a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution, more preferably a sodium hydroxide aqueous solution.
  • This step is necessary to disperse the single-walled carbon nanotubes and carbon fine particles physically separated by the acid treatment in the liquid, and the functional groups such as carboxyl groups generated by the acid treatment are converted into salts. This increases the dispersibility.
  • the surfactant used here is not particularly limited as long as it is a known surfactant, and any anionic, nonionic or cationic surfactant can be used.
  • any anionic, nonionic or cationic surfactant can be used.
  • sodium dodecylbenzenesulfonate or polyethylene glycol monooctylphenyl ether is usable.
  • Polyethylene glycol monooctyl phenyl ether is more preferable.
  • the acid treatment after the alkali treatment is not particularly limited as long as it is as described above, but hydrochloric acid is more preferable. Among these, it is more preferable to carry out at room temperature.
  • the functional group of the single-walled carbon nanotube that has been converted to a salt by the alkali treatment such as an alkali metal salt of a carboxyl group, is converted into a carboxyl group.
  • the alkali-treated single-walled carbon nanotube dispersion liquid may be directly acid-treated, or the single-walled carbon nanotube dispersion liquid is applied onto a substrate to obtain a conductive layer. Thereafter, acid treatment may be performed. By this step, a transparent conductive film composed of single-walled carbon nanotubes with high heat resistance is obtained.
  • the conductive film according to the present invention is more preferably one in which single-walled carbon nanotubes are alkali-treated after acid treatment and acid-treated after filtration with a hollow fiber membrane.
  • the filtration step is a preferable step for removing the carbon fine particles contained in the production of the single-walled carbon nanotubes, improving the purity of the single-walled carbon nanotubes, and obtaining a more transparent conductive film.
  • the timing of performing the filtration step in the present invention is important. If the filtration process is carried out before the alkali treatment, the single-walled carbon nanotubes and the carbon fine particles are not sufficiently dispersed in the liquid and the purity is difficult to increase. On the other hand, the filtration is performed after the acid treatment process after the alkali treatment is completed. The purity is difficult to increase for the reason. Therefore, the filtration step is performed after the acid treatment and after the alkali treatment, and at the timing before the acid treatment after the alkali treatment.
  • the filtration method is not particularly limited as long as it is a known method, and suction filtration, pressure filtration, crossflow filtration and the like can be used. Among these, from the viewpoint of scale-up, cross flow filtration using a hollow fiber membrane is more preferable.
  • the step of subjecting single-walled carbon nanotubes to alkali treatment after acid treatment is known as a method for improving the dispersibility of single-walled carbon nanotubes (Non-Patent Document 1), and as described above, this step is introduced by acid treatment.
  • the resulting functional group (mainly hydroxyl group) is neutralized by subsequent alkali treatment to form a salt.
  • this is further neutralized or acidified by acid treatment, the dispersibility is lowered, and it is difficult to prepare a dispersion of single-walled carbon nanotubes, and it is difficult to manufacture a conductive film using this. Therefore, it is not usually assumed that a conductive film is produced using neutral or acidic single-walled carbon nanotubes.
  • the transparent conductive film used in the present invention contains fullerene or an analog thereof.
  • fullerene or an analog thereof single-walled carbon nanotubes that have not been subjected to alkali treatment, or once subjected to alkali treatment and then acid treatment have low dispersibility, and thus a dispersion for producing a transparent conductive film is obtained.
  • some kind of distributed processing is required.
  • it is possible to disperse using a known surfactant it is easier to disperse carbon nanotubes using fullerene and its analogs.
  • the heat resistance of an electrically conductive film improves also by containing fullerene and its analog.
  • the fullerene used in the present invention may be any fullerene. Examples thereof include C60, C70, C76, C78, C82, C84, C90, and C96. Of course, a mixture of these plural types of fullerenes may be used. In addition, C60 is particularly preferable from the viewpoint of dispersibility. Furthermore, C60 is easy to obtain. Further, not only C60, but also a mixture of C60 and another type of fullerene (for example, C70) may be used. Further, metal atoms may be appropriately included in the fullerene.
  • the fullerene preferably has a polar group, and more preferably has an OH group (hydroxyl group). This is because single-walled carbon nanotubes have high dispersibility.
  • the dispersibility improvement degree of a single-walled carbon nanotube will fall, and if too large, a synthesis
  • the polar group is a hydroxyl group
  • the amount of the hydroxyl group is preferably 5 to 30 and more preferably 8 to 15 per fullerene molecule.
  • the conductive film of the present invention provides an electrode having a conductive film and a protective layer on a substrate.
  • the substrate used in the present invention is not particularly limited as long as it is in the form of a sheet or film, but for example, ceramics such as glass and alumina, metals such as iron, aluminum and copper, polyester resins, cellulose resins, vinyls Examples include alcohol resins, vinyl chloride resins, cycloolefin resins, polycarbonate resins, acrylic resins, ABS resins, and other thermoplastic resins, photocurable resins, thermosetting resins, and the like.
  • the total light transmittance of the substrate is preferably 80% or more.
  • the preferred range of the thickness of the substrate varies depending on the use, but it is preferably 500 ⁇ m or more and 10 mm or less in the case of a sheet, and preferably 10 ⁇ m or more and 500 ⁇ m or less in the case of a film.
  • Thermoplastic resins such as a polyester resin, a cellulose resin, a vinyl alcohol resin, a vinyl resin, a cycloolefin resin, a polycarbonate resin, an acrylic resin, an ABS resin, a photocurable resin
  • a known coating material such as a thermosetting resin can be used.
  • the material of the protective layer is preferably the same material as the base material from the viewpoint of adhesion.
  • the base material is a polyester resin
  • the protective layer is preferably a polyester resin.
  • the thickness of the protective layer is too thick, the contact resistance of the conductive layer increases, and if it is too thin, the effect as the protective layer cannot be obtained, and is preferably 1 nm or more and 1 ⁇ m or less, and more preferably 10 nm or more and 100 nm or less.
  • the present invention further relates to a method for producing a single-walled carbon nanotube dispersion, wherein step 1: a step of obtaining a crude carbon nanotube, step 2: a step of acid-treating the crude carbon nanotube, step 3: a single-layer obtained in step 2 Step of alkali-treating carbon nanotubes, Step 4: Step of filtering single-walled carbon nanotubes obtained in Step 3 using a hollow fiber membrane, Step 5: Step of acid-treating single-walled carbon nanotubes obtained in Step 4 A method for producing a single-walled carbon nanotube dispersion liquid is provided.
  • Step 1 The step of obtaining the crude carbon nanotube is not particularly limited as long as it is a known production method, and any production method such as an arc discharge method, a chemical vapor deposition method, or a laser evaporation method can be used. From the viewpoint of crystallinity, the production method by the arc discharge method is most preferable.
  • Step 2 The step of acid-treating the crude carbon nanotube is a method of heating the single-walled carbon nanotube in an acidic liquid.
  • the acidic liquid is not particularly limited as long as it is a known compound, and specific examples include nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, and mixtures thereof.
  • the acid treatment prior to the alkali treatment is preferably acid treatment using nitric acid or a mixed solution of nitric acid and sulfuric acid, more preferably 80 to 100 ° C., more preferably 1 to 7 days. More preferred.
  • Step 3 The step of alkali-treating the single-walled carbon nanotubes obtained in Step 2 is a method of immersing the single-walled carbon nanotubes in an alkaline liquid.
  • the alkaline liquid is not particularly limited as long as it is a known one, and specific examples include an aqueous lithium hydroxide solution, an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution, an aqueous ammonia solution, and an alkylamine aqueous solution such as propylamine and butylamine.
  • the alkaline liquid used during the alkali treatment is preferably a lithium hydroxide aqueous solution, a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution, more preferably a sodium hydroxide aqueous solution.
  • Step 4 The step of filtering the single-walled carbon nanotubes obtained in Step 3 is a step of removing impurities such as carbon particles.
  • the reaction solution of carbon nanotubes subjected to the acid treatment is dispersed or precipitated in the solution in a state in which impurity particles having a diameter of about 20 nm and carbon nanotube bundles are separated. For this reason, the impurities can be removed by filtering using a filter having a pore size larger than the impurities and smaller than the bundle of carbon nanotubes.
  • the filtration method is not particularly limited as long as it is a known filtration method, and suction filtration, pressure filtration, crossflow filtration, or the like can be used. Among these, from the viewpoint of scale-up, cross flow filtration using a hollow fiber membrane is more preferable.
  • Step 5 The step of acid-treating the single-walled carbon nanotubes obtained in Step 4 is a method of immersing the single-walled carbon nanotubes in an acidic liquid.
  • the acidic liquid is not particularly limited as long as it is a known compound, and specific examples include nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, and mixtures thereof. Of these, hydrochloric acid is more preferable. Furthermore, it is more preferable to carry out at room temperature.
  • the method for producing a single-walled carbon nanotube dispersion of the present invention is not particularly limited as long as it includes the above-mentioned steps 1 to 5, but for example, the single-walled carbon nanotube obtained in step 5 after step 5 and fullerene or the like. It is also possible to mix the body and irradiate with ultrasonic waves.
  • the ratio of the single-walled carbon nanotube and fullerene is not particularly limited, but the fullerene is preferably 10 to 1000 parts by weight with respect to 100 parts by weight of the single-walled carbon nanotube.
  • the fullerene concentration is preferably 1 to 100,000 ppm.
  • the fullerene is particularly preferably a fullerene having an OH group.
  • a method for irradiating ultrasonic waves there is no particular limitation as long as it is a known method, and it is possible to use a bath type ultrasonic irradiator or a chip type ultrasonic irradiator. From the viewpoint of processing in a shorter time, a chip. It is more preferable to use a type ultrasonic irradiator.
  • the solvent used in the present invention is not limited as long as it is a solvent used in general paints.
  • a solvent having a boiling point of 200 ° C. or lower preferably lower limit is 25 ° C., further 30 ° C.
  • the low boiling point solvent is preferred because it is easy to dry after coating.
  • water, alcohol compounds such as methanol, ethanol, normal propanol, and isopropanol (particularly alcohols having 7 or less carbon atoms, particularly aliphatic alcohols), or a mixture thereof are preferable. This is because the hydroxyl group-containing fullerene has a high solubility, so that a single-walled carbon nanotube dispersion with a higher concentration can be obtained.
  • ketone compounds such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone
  • ester compounds such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, methoxyethyl acetate, diethyl ether, ethylene glycol dimethyl ether, ethyl cellosolve , Ether compounds such as butyl cellosolve, phenyl cellosolve and dioxane, aromatic compounds such as toluene and xylene, aliphatic compounds such as pentane and hexane, halogenated hydrocarbons such as methylene chloride, chlorobenzene and chloroform, and mixtures thereof
  • ester compounds such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, methoxyethyl acetate, dieth
  • a conductive film can be manufactured by apply
  • drying is performed to remove the solvent contained in the coating film.
  • a drying apparatus used for example, a heating furnace, a far-infrared furnace, a super far-infrared furnace, etc. that are usually used for drying can be used.
  • the conductive film of the present invention can also be produced by applying the single-walled carbon nanotube dispersion liquid obtained up to step 4 on the substrate by the above-described method and acid-treating the obtained conductive layer.
  • it can.
  • Specific examples include a method of spraying and applying an acidic liquid to the conductive layer, a method of immersing the conductive layer in an acidic liquid, and the like.
  • the acidic liquid is not particularly limited as long as it is a known compound, and specific examples include nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, and mixtures thereof. Of these, hydrochloric acid is more preferable. Furthermore, it is more preferable to carry out at room temperature. It is also possible to remove the remaining acidic liquid by washing the conductive layer with alcohols such as methanol or pure water.
  • a conductive film is obtained as described above. Specifically, a transparent conductive film having a total light transmittance of 60% or more and a surface resistance value of 10,000 ⁇ / ⁇ or less is obtained. Furthermore, a transparent conductive film having a total light transmittance of 70% or more and a surface resistance value of 3000 ⁇ / ⁇ or less can be obtained easily and at low cost.
  • the total light transmittance is the total light transmittance including not only the conductive film containing single-walled carbon nanotubes but also the substrate.
  • the conductive film having the features described above can be used for an electrode substrate for a touch panel, an electrode substrate for electronic paper, an electrode substrate for a liquid crystal display, an electrode substrate for a plasma display, and the like.
  • Example 1 A 5 L separable flask was charged with 30 g of crude single-walled carbon nanotubes obtained by an arc discharge method and 300 ml of distilled water, and the crude single-walled carbon nanotubes were completely wetted with distilled water. While stirring with a mechanical stirrer, 2700 ml of 69% nitric acid (manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise, followed by stirring at 85 ° C. for 48 hours.
  • the solid content was recovered by a centrifuge (product name: CR26H, manufactured by Hitachi Koki Co., Ltd.) and put into 6000 ml of an aqueous sodium hydroxide solution (pH 10). Furthermore, polyethylene glycol monooctylphenyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) was added so as to be 0.5 wt%, and ultrasonic waves were applied using a cone type ultrasonic irradiator (device name: ULTRASONIC HOMOGENIZER MODEL UH-600SR, manufactured by SMT Corporation). Was irradiated for 5 minutes. The reaction solution was centrifuged at 13000 rpm for 1 hour using a centrifuge, and the supernatant was recovered to obtain a crude purified solution.
  • a centrifuge product name: CR26H, manufactured by Hitachi Koki Co., Ltd.
  • polyethylene glycol monooctylphenyl ether manufactured by Tokyo Chemical Industry Co.,
  • the crude purified solution was subjected to cross flow filtration.
  • the hollow fiber membrane module used has a pore size of 200 nm and a membrane area of 5800 cm 2 (manufactured by SPECTRUM). Alkaline aqueous solution.
  • the crude purified solution was washed with 120.0 L of washing solution to obtain 6000 ml of a purified single-walled carbon nanotube dispersion.
  • the obtained dispersion was spray coated on a polycarbonate plate. Further, the coated surface was washed with methanol and dried at 80 ° C. for 3 minutes. Further, it was immersed in a 0.1 M hydrochloric acid solution for 1 minute, washed with methanol and then dried at 80 ° C. for 3 minutes to obtain a polycarbonate plate with a conductive layer.
  • Example 2 After neutralizing 1M hydrochloric acid to pH 4 to 100 ml of the purified single-walled carbon nanotube dispersion obtained in Example 1, 100 ml of isopropyl alcohol was added, and the single-walled carbon nanotubes were recovered in a solid state with a centrifuge. did.
  • the obtained single-walled carbon nanotube 10 mg of hydroxyl group-containing fullerene (trade name: Nanomuspectra D-100 Frontier Carbon Co., Ltd .: C60 fullerene), 1 mg of sodium hydroxide (Wako Pure Chemical Industries, Ltd.), 50 ml of water, isopropyl Single-walled carbon nanotubes are mixed with 50 ml of alcohol and irradiated with ultrasonic waves for 1 minute using an ultrasonic device (ULTRASONIC HOMOGENIZER MODEL UH-600SR, manufactured by SMT Co., Ltd.). A dispersion was obtained.
  • ULTRASONIC HOMOGENIZER MODEL UH-600SR manufactured by SMT Co., Ltd.
  • the obtained single-walled carbon nanotube dispersion was applied to a hard-coated polycarbonate substrate by a bar coating method.
  • the thickness is 50 ⁇ m in wet film thickness. Then, it was dried at 80 ° C. for 3 minutes, and the surface was washed with methanol. Furthermore, it was dried at 80 ° C. for 3 minutes to obtain a polycarbonate plate with a conductive layer.
  • Example 3 On the polycarbonate plate with a conductive layer obtained in Example 2, an acrylic resin (trade name: WATERSOL S-707IM, manufactured by Dainippon Ink & Chemicals, Inc.) was laminated as a protective layer. Specifically, the acrylic resin was dip-coated as a 1% by mass isopropyl alcohol solution and then dried at 80 ° C. for 3 minutes.
  • WATERSOL S-707IM manufactured by Dainippon Ink & Chemicals, Inc.
  • Example 1 The dispersion of purified single-walled carbon nanotubes obtained in Example 1 was spray coated on a polycarbonate plate. Further, the coated surface was washed with methanol and dried at 80 ° C. for 3 minutes to obtain a polycarbonate plate with a conductive layer. Further, an acrylic resin (trade name: WATERSOL S-707IM, manufactured by Dainippon Ink & Chemicals, Inc.) was laminated as a protective layer. Specifically, the acrylic resin was dip-coated as a 1% by mass isopropyl alcohol solution and then dried at 80 ° C. for 3 minutes.
  • WATERSOL S-707IM manufactured by Dainippon Ink & Chemicals, Inc.
  • the electrically conductive film of this invention is excellent in translucency.
  • it is excellent in conductivity, has low deterioration at high temperatures, and is excellent in durability.

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Abstract

Provided are an electrically conductive film comprising a single layer of carbon nanotubes, having a high heat resistance, and a method of producing a liquid dispersion of carbon nanotubes for production of said film.  The single layer carbon nanotubes are acid treated and then alkali treated and finally acid treated again.  After acid treatment for refinement purposes, an alkali treatment is carried out to improve dispersibility and then another acid treatment is carried out.  The heat resistance of the transparent electrically conductive film obtained is improved by this means.

Description

カーボンナノチューブを用いた導電膜およびその製造方法Conductive film using carbon nanotube and method for producing the same
　本発明は透明電極などに用いるための透明な導電膜及びその製造方法に関するものである。より詳しくは、酸処理後アルカリ処理され、さらに酸処理した単層カーボンナノチューブを用いた導電膜及びその製造方法に関するものである。 The present invention relates to a transparent conductive film for use in a transparent electrode or the like and a method for producing the same. More specifically, the present invention relates to a conductive film using single-walled carbon nanotubes that have been acid-treated, alkali-treated, and acid-treated, and a method for producing the same.
　従来単層カーボンナノチューブを用いた透明導電膜が提案されているが、アーク放電法や化学気相蒸着法によって得られる単層カーボンナノチューブは純度が低く精製する工程が必要である。精製方法には大きく分けて空気中で加熱する乾式法と酸性液体中で加熱する湿式法があるが、乾式法は収率が低いため湿式法が有力な単層カーボンナノチューブの精製方法である（特許文献１）。 Conventionally, a transparent conductive film using single-walled carbon nanotubes has been proposed, but single-walled carbon nanotubes obtained by an arc discharge method or a chemical vapor deposition method require a purification process with low purity. The purification method is roughly divided into a dry method in which heating is performed in air and a wet method in which heating is performed in an acidic liquid. However, the dry method is a method for purifying single-walled carbon nanotubes because of its low yield. Patent Document 1).
　しかしながら、湿式法で精製した単層カーボンナノチューブで作製した透明導電膜は高温下で長時間放置すると導電性が低下するという問題点があった。
　対策として我々は既にスルホン酸基含有樹脂を保護層として設ける方法や、カーボンナノチューブの官能基をカルボン酸金属塩とする方法を報告している（特許文献２、３）。また保護層を設ける方法（特許文献４、５）が開示されている。保護層を設ける方法（特許文献４、５）は有効な対策であり、保護層がない場合に比べ耐熱性は向上するものの、十分な性能は得られていなかった。 However, a transparent conductive film made of single-walled carbon nanotubes purified by a wet method has a problem in that the conductivity decreases when left for a long time at a high temperature.
As countermeasures, we have already reported a method in which a sulfonic acid group-containing resin is provided as a protective layer and a method in which a functional group of a carbon nanotube is a carboxylic acid metal salt (Patent Documents 2 and 3). Moreover, the method (patent documents 4, 5) which provides a protective layer is disclosed. The method of providing the protective layer (Patent Documents 4 and 5) is an effective measure, and although heat resistance is improved as compared with the case without the protective layer, sufficient performance has not been obtained.
特開２００２－５１５８４７号公報JP 2002-515847 A 特願２００７－０８９１７８号明細書Japanese Patent Application No. 2007-089178 特願２００７－０８９１７９号明細書Japanese Patent Application No. 2007-089179 特開２００４－２０２９４８号公報JP 2004-202948 A 特開２００５－２５５９８５号公報JP 2005-255985 A
　すなわち本発明の課題は、耐熱性の高い単層カーボンナノチューブからなる導電膜およびそれを製造するためのカーボンナノチューブ分散液の製造方法を提供することである。 That is, an object of the present invention is to provide a conductive film composed of single-walled carbon nanotubes having high heat resistance and a method for producing a carbon nanotube dispersion for producing the conductive film.
　本発明者らは、単層カーボンナノチューブからなる導電膜の耐熱性を本質的に改善すべく鋭意検討した結果、カーボンナノチューブに付与される官能基は、塩でないことが耐熱性の向上に有効であるということを見出した。つまり、酸処理後アルカリ処理され、さらに酸処理された単層カーボンナノチューブを使用することによって耐熱性の高い導電膜が得られることを見出し、さらに検討を重ねた結果、上記課題を解決し得る導電膜を完成するに至った。 As a result of intensive studies to essentially improve the heat resistance of the conductive film composed of single-walled carbon nanotubes, the present inventors have found that the functional group imparted to the carbon nanotubes is effective in improving heat resistance if it is not a salt. I found out that there is. In other words, it has been found that a conductive film having high heat resistance can be obtained by using single-walled carbon nanotubes that have been acid-treated, alkali-treated, and further acid-treated, and as a result of further studies, conductive that can solve the above problems. The film was completed.
　すなわち本発明は、単層カーボンナノチューブを含む導電膜であって、該単層カーボンナノチューブが酸処理後アルカリ処理され、さらに酸処理されて得られるものであることを特徴とする導電膜である。
　また、本発明において該導電膜は、フラーレンまたはその類縁体を含むことが好ましい。
　さらに本発明は基板上に上記導電膜と保護層を有することを特徴とする電極である。 That is, the present invention is a conductive film containing single-walled carbon nanotubes, wherein the single-walled carbon nanotubes are obtained by acid treatment, alkali treatment, and further acid treatment.
In the present invention, the conductive film preferably contains fullerene or an analog thereof.
Furthermore, the present invention is an electrode comprising the conductive film and a protective layer on a substrate.
　また本発明は、単層カーボンナノチューブ分散液の製法であって、工程１：粗カーボンナノチューブを得る工程、工程２：粗カーボンナノチューブを酸処理する工程、工程３：工程２で得られた単層カーボンナノチューブをアルカリ処理する工程、工程４：工程３で得られた単層カーボンナノチューブをろ過する工程、工程５：工程４で得られた単層カーボンナノチューブを酸処理する工程を含むことを特徴とする単層カーボンナノチューブ分散液の製造方法およびこの製造方法によって得られたカーボンナノチューブ分散液を用いることを特徴とする導電膜の製造方法である。 The present invention also relates to a method for producing a single-walled carbon nanotube dispersion, wherein step 1: a step of obtaining a crude carbon nanotube, step 2: a step of acid-treating the crude carbon nanotube, step 3: a single-layer obtained in step 2 A step of alkali-treating carbon nanotubes, step 4: a step of filtering single-walled carbon nanotubes obtained in step 3, and step 5: a step of acid-treating single-walled carbon nanotubes obtained in step 4 A method for producing a conductive film, characterized by using a method for producing a single-walled carbon nanotube dispersion and a carbon nanotube dispersion obtained by the production method.
　また本発明は、単層カーボンナノチューブを含む導電膜の製造方法であって、工程１：粗カーボンナノチューブを得る工程；工程２：粗カーボンナノチューブを酸処理する工程；工程３：工程２で得られた単層カーボンナノチューブをアルカリ処理する工程；および工程４：工程３で得られた単層カーボンナノチューブをろ過する工程；を含む単層カーボンナノチューブを含む分散液を得る工程Ａ；工程Ａで得られた単層カーボンナノチューブを基板上に塗布して導電層を得る工程Ｂ；並びに、工程Ｂで得られた導電層を酸処理する工程Ｃ；を含むことを特徴とする単層カーボンナノチューブ含む導電膜の製造方法である。 The present invention also relates to a method for producing a conductive film containing single-walled carbon nanotubes, which is obtained in Step 1: Step of obtaining crude carbon nanotubes; Step 2: Step of treating crude carbon nanotubes with acid; Step 3: Step 2. Obtained in step A; a step of obtaining a dispersion containing single-walled carbon nanotubes; and a step of filtering the single-walled carbon nanotubes obtained in step 3; A conductive film containing single-walled carbon nanotubes, comprising: a step B of applying a single-walled carbon nanotube on a substrate to obtain a conductive layer; and a step C of acid-treating the conductive layer obtained in step B. It is a manufacturing method.
　本発明による単層カーボンナノチューブからなる透明な導電膜は高温耐久性を有するため、液晶画面などの各種ディスプレイやタッチパネルなどの電極部材として有利に利用することができる。 The transparent conductive film made of single-walled carbon nanotubes according to the present invention has high-temperature durability and can be advantageously used as an electrode member for various displays such as liquid crystal screens and touch panels.
　また、安価な原料であるアーク放電法によって得られた単層カーボンナノチューブを利用することができ、さらに工業的スケールで精製することができる酸処理法を利用することができるので、透明な導電膜を安定して供給することができる。 In addition, a single-walled carbon nanotube obtained by an arc discharge method, which is an inexpensive raw material, can be used, and an acid treatment method that can be purified on an industrial scale can be used. Can be supplied stably.
　本発明は単層カーボンナノチューブを含む導電膜であって、該単層カーボンナノチューブが酸処理後アルカリ処理され、さらに酸処理したものであることを特徴とする導電膜である。 The present invention is a conductive film containing single-walled carbon nanotubes, wherein the single-walled carbon nanotubes are acid-treated, alkali-treated, and further acid-treated.
　本発明に用いる単層カーボンナノチューブは公知の製法によって得られた単層カーボンナノチューブであれば特に制限はなく、アーク放電法、化学気相蒸着法、レーザー蒸発法などいずれの製法も利用することができるが、入手容易性と結晶性の観点からアーク放電法による製造法が最も好ましい。 The single-walled carbon nanotube used in the present invention is not particularly limited as long as it is a single-walled carbon nanotube obtained by a known production method, and any production method such as an arc discharge method, a chemical vapor deposition method, or a laser evaporation method can be used. However, the production method by the arc discharge method is most preferable from the viewpoint of availability and crystallinity.
　本発明において酸処理とは酸性液体中に単層カーボンナノチューブを浸漬する方法の総称である。酸性液体は公知の化合物であれば特に制限はなく、具体的には硝酸、塩酸、硫酸、リン酸及びこれらの混合物が挙げられる。 In the present invention, acid treatment is a general term for a method of immersing single-walled carbon nanotubes in an acidic liquid. The acidic liquid is not particularly limited as long as it is a known compound, and specific examples include nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, and mixtures thereof.
　本発明においてアルカリ処理前の酸処理は硝酸あるいは硝酸と硫酸の混合液を用いた酸処理が好ましく、８０℃以上１００℃以下で反応させることがより好ましく、１日以上７日間以下反応させることがより好ましい。
　この工程は単層カーボンナノチューブと炭素微粒子がアモルファスカーボンを介して物理的に結合している場合にアモルファスカーボンを分解することによって両者を分離したり、単層カーボンナノチューブ作製時に使用した金属触媒の微粒子を分解したりするために必要な工程である。 In the present invention, the acid treatment prior to the alkali treatment is preferably acid treatment using nitric acid or a mixed solution of nitric acid and sulfuric acid, more preferably 80 to 100 ° C., more preferably 1 to 7 days. More preferred.
In this process, when the single-walled carbon nanotubes and carbon fine particles are physically bonded via amorphous carbon, the amorphous carbon is decomposed to separate them, or the metal catalyst fine particles used when producing the single-walled carbon nanotubes It is a process necessary for disassembling.
　本発明においてアルカリ処理とは単層カーボンナノチューブをアルカリ性液体中に浸漬させる方法の総称である。アルカリ性液体は公知のものであれば特に制限はなく具体的には水酸化リチウム水溶液、水酸化ナトリウム水溶液、水酸化カリウム水溶液、アンモニア水溶液、プロピルアミン、ブチルアミンなどのアルキルアミン水溶液などが挙げられる。
　本発明においてアルカリ処理時に用いるアルカリ性液体は水酸化リチウム水溶液、水酸化ナトリウム水溶液、水酸化カリウム水溶液が好ましく、水酸化ナトリウム水溶液がより好ましい。 In the present invention, the alkali treatment is a general term for a method of immersing single-walled carbon nanotubes in an alkaline liquid. The alkaline liquid is not particularly limited as long as it is a known one, and specific examples include an aqueous lithium hydroxide solution, an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution, an aqueous ammonia solution, and an alkylamine aqueous solution such as propylamine and butylamine.
In the present invention, the alkaline liquid used during the alkali treatment is preferably a lithium hydroxide aqueous solution, a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution, more preferably a sodium hydroxide aqueous solution.
　この工程は酸処理で物理的に分離された単層カーボンナノチューブや炭素微粒子を液体中に分散させるために必要な工程であり、前記酸処理にて発生したカルボキシル基などの官能基を塩にすることでより分散性を上げている。 This step is necessary to disperse the single-walled carbon nanotubes and carbon fine particles physically separated by the acid treatment in the liquid, and the functional groups such as carboxyl groups generated by the acid treatment are converted into salts. This increases the dispersibility.
　この趣旨に基づいてさらに界面活性剤などを添加して単層カーボンナノチューブや炭素微粒子の分散性をさらに向上させることも可能である。
　この際用いる界面活性剤は公知のものであれば特に制限はなくアニオン系、ノニオン系、カチオン系いずれの界面活性剤も使用できるが具体的にはドデシルベンゼンスルホン酸ナトリウムやポリエチレングリコールモノオクチルフェニルエーテルなどが挙げられ、ポリエチレングリコールモノオクチルフェニルエーテルがより好ましい。 Based on this purpose, it is also possible to further improve the dispersibility of the single-walled carbon nanotubes or carbon fine particles by adding a surfactant or the like.
The surfactant used here is not particularly limited as long as it is a known surfactant, and any anionic, nonionic or cationic surfactant can be used. Specifically, sodium dodecylbenzenesulfonate or polyethylene glycol monooctylphenyl ether is usable. Polyethylene glycol monooctyl phenyl ether is more preferable.
　本発明においてアルカリ処理後の酸処理は上述のものであれば特に制限はないが、塩酸がより好ましい。なかでも室温状態で行なうことがより好ましい。この工程によりアルカリ処理によって塩となった単層カーボンナノチューブの官能基、例えばカルボキシル基のアルカリ金属塩などをカルボキシル基にする。 In the present invention, the acid treatment after the alkali treatment is not particularly limited as long as it is as described above, but hydrochloric acid is more preferable. Among these, it is more preferable to carry out at room temperature. In this step, the functional group of the single-walled carbon nanotube that has been converted to a salt by the alkali treatment, such as an alkali metal salt of a carboxyl group, is converted into a carboxyl group.
　このアルカリ処理後の酸処理は、アルカリ処理を行なった単層カーボンナノチューブ分散液を直接酸処理しても良いし、前記単層カーボンナノチューブ分散液を基板上に塗布して、導電層を得た後、酸処理を行なっても良い。
　この工程によって耐熱性の高い単層カーボンナノチューブからなる透明な導電膜が得られる。 In the acid treatment after the alkali treatment, the alkali-treated single-walled carbon nanotube dispersion liquid may be directly acid-treated, or the single-walled carbon nanotube dispersion liquid is applied onto a substrate to obtain a conductive layer. Thereafter, acid treatment may be performed.
By this step, a transparent conductive film composed of single-walled carbon nanotubes with high heat resistance is obtained.
　本発明による導電膜は単層カーボンナノチューブが酸処理後アルカリ処理され、中空糸膜によるろ過後に酸処理したものであることがより好ましい。
　ろ過工程は単層カーボンナノチューブ製造時に含まれる炭素微粒子を取り除き、単層カーボンナノチューブの純度を向上させ、より透明性の高い導電膜を得るために好ましい工程である。 The conductive film according to the present invention is more preferably one in which single-walled carbon nanotubes are alkali-treated after acid treatment and acid-treated after filtration with a hollow fiber membrane.
The filtration step is a preferable step for removing the carbon fine particles contained in the production of the single-walled carbon nanotubes, improving the purity of the single-walled carbon nanotubes, and obtaining a more transparent conductive film.
　ただし、本発明においてろ過工程を行なうタイミングは重要である。ろ過工程をアルカリ処理前に行なうと単層カーボンナノチューブや炭素微粒子が液中に十分に分散されておらず純度が上がりにくく、一方、アルカリ処理後の酸処理工程を終えた後にろ過を行なうと同様の理由で純度が上がりにくい。従って、ろ過工程は酸処理後アルカリ処理された後であって、かつ、アルカリ処理後の酸処理前のタイミングで行なう。 However, the timing of performing the filtration step in the present invention is important. If the filtration process is carried out before the alkali treatment, the single-walled carbon nanotubes and the carbon fine particles are not sufficiently dispersed in the liquid and the purity is difficult to increase. On the other hand, the filtration is performed after the acid treatment process after the alkali treatment is completed. The purity is difficult to increase for the reason. Therefore, the filtration step is performed after the acid treatment and after the alkali treatment, and at the timing before the acid treatment after the alkali treatment.
　ろ過の方法は公知の方法であれば特に制限はなく、吸引ろ過や加圧ろ過、クロスフローろ過などを用いることができる。中でもスケールアップの観点からは中空糸膜を用いたクロスフローろ過がより好ましい。 The filtration method is not particularly limited as long as it is a known method, and suction filtration, pressure filtration, crossflow filtration and the like can be used. Among these, from the viewpoint of scale-up, cross flow filtration using a hollow fiber membrane is more preferable.
　ここで、単層カーボンナノチューブを酸処理後アルカリ処理する工程は、単層カーボンナノチューブの分散性を向上させる方法として公知であり（非特許文献１）、上述したようにこの工程では酸処理により導入された官能基（主に水酸基）が続くアルカリ処理によって中和され塩を形成する。これをさらに酸処理により中和あるいは酸性にすると分散性が低下し、単層カーボンナノチューブの分散液を作製することが難しく、これを用いた導電膜を作製することは困難であった。従って、通常、中性あるいは酸性状態の単層カーボンナノチューブを用いて導電膜を作製することは想定されていない。 Here, the step of subjecting single-walled carbon nanotubes to alkali treatment after acid treatment is known as a method for improving the dispersibility of single-walled carbon nanotubes (Non-Patent Document 1), and as described above, this step is introduced by acid treatment. The resulting functional group (mainly hydroxyl group) is neutralized by subsequent alkali treatment to form a salt. When this is further neutralized or acidified by acid treatment, the dispersibility is lowered, and it is difficult to prepare a dispersion of single-walled carbon nanotubes, and it is difficult to manufacture a conductive film using this. Therefore, it is not usually assumed that a conductive film is produced using neutral or acidic single-walled carbon nanotubes.
　そこで、本発明において用いる透明導電膜はフラーレンまたはその類縁体を含むことがより好ましい。前述のとおり、アルカリ処理を施していなかったり、一旦アルカリ処理を施した後、酸処理を行なったりした単層カーボンナノチューブは分散性が低いため、透明な導電膜を作製するための分散液を得るためには何らかの分散処理が必要である。ここで、公知の界面活性剤を用いて分散させることも可能であるが、フラーレン及びその類縁体を用いる方がより容易にカーボンナノチューブを分散させることができる。また、フラーレン及びその類縁体を含有することで導電膜の耐熱性も向上するからである。 Therefore, it is more preferable that the transparent conductive film used in the present invention contains fullerene or an analog thereof. As described above, single-walled carbon nanotubes that have not been subjected to alkali treatment, or once subjected to alkali treatment and then acid treatment have low dispersibility, and thus a dispersion for producing a transparent conductive film is obtained. For this purpose, some kind of distributed processing is required. Here, although it is possible to disperse using a known surfactant, it is easier to disperse carbon nanotubes using fullerene and its analogs. Moreover, it is because the heat resistance of an electrically conductive film improves also by containing fullerene and its analog.
　本発明で用いられるフラーレンは、フラーレンならば如何なるものでも良い。例えば、Ｃ６０，Ｃ７０，Ｃ７６，Ｃ７８，Ｃ８２，Ｃ８４，Ｃ９０，Ｃ９６等のものが挙げられる。もちろん、これ等複数種のフラーレンの混合物でも良い。なお、分散性の観点からＣ６０のものが特に好ましい。更に、Ｃ６０のものは入手し易い。また、Ｃ６０のもののみでは無く、Ｃ６０と他の種類のフラーレン（例えば、Ｃ７０）との混合物でも良い。また、フラーレンの内部に、適宜、金属原子を内包したものでも良い。フラーレンは、極性基を持つのが好ましく、ＯＨ基（水酸基）を持つものがより好ましい。それは、単層カーボンナノチューブの分散性が高いからである。そして、極性基の量が少ないと、単層カーボンナノチューブの分散性向上度が低下し、多すぎると、合成が困難である。例えば、極性基が水酸基の場合、水酸基の量はフラーレン１分子当り５～３０個が好ましく、８～１５個がより好ましい。 The fullerene used in the present invention may be any fullerene. Examples thereof include C60, C70, C76, C78, C82, C84, C90, and C96. Of course, a mixture of these plural types of fullerenes may be used. In addition, C60 is particularly preferable from the viewpoint of dispersibility. Furthermore, C60 is easy to obtain. Further, not only C60, but also a mixture of C60 and another type of fullerene (for example, C70) may be used. Further, metal atoms may be appropriately included in the fullerene. The fullerene preferably has a polar group, and more preferably has an OH group (hydroxyl group). This is because single-walled carbon nanotubes have high dispersibility. And if there is little quantity of a polar group, the dispersibility improvement degree of a single-walled carbon nanotube will fall, and if too large, a synthesis | combination will be difficult. For example, when the polar group is a hydroxyl group, the amount of the hydroxyl group is preferably 5 to 30 and more preferably 8 to 15 per fullerene molecule.
　さらに本発明の導電膜は、基板上に導電膜と保護層を有する電極を提供する。
　本発明において用いる基材としてはシート状、フィルム状のものであれば特に制限はないが、例えば、ガラス、アルミナなどのセラミックや、鉄、アルミ、銅等の金属、ポリエステル樹脂、セルロース樹脂、ビニルアルコール樹脂、塩化ビニル樹脂、シクロオレフィン系樹脂、ポリカーボネート樹脂、アクリル樹脂、ＡＢＳ樹脂等の熱可塑性樹脂、光硬化性樹脂、熱硬化性樹脂などが挙げられ、本発明による導電膜を使用するに際して透明性を重視する場合には、上記基材の全光線透過率が８０％以上であることが好ましい。具体的には、ガラス、ポリエステル樹脂、ポリカーボネート樹脂、アクリル樹脂、セルロース樹脂などが挙げられる。
　上記基材の厚みは用途によって好ましい範囲は異なるが、シート状であれば５００μｍ以上１０ｍｍ以下が好ましく、フィルム状であれば１０μｍ以上５００μｍ以下が好ましい。 Furthermore, the conductive film of the present invention provides an electrode having a conductive film and a protective layer on a substrate.
The substrate used in the present invention is not particularly limited as long as it is in the form of a sheet or film, but for example, ceramics such as glass and alumina, metals such as iron, aluminum and copper, polyester resins, cellulose resins, vinyls Examples include alcohol resins, vinyl chloride resins, cycloolefin resins, polycarbonate resins, acrylic resins, ABS resins, and other thermoplastic resins, photocurable resins, thermosetting resins, and the like. When importance is attached to the properties, the total light transmittance of the substrate is preferably 80% or more. Specific examples include glass, polyester resin, polycarbonate resin, acrylic resin, and cellulose resin.
The preferred range of the thickness of the substrate varies depending on the use, but it is preferably 500 μm or more and 10 mm or less in the case of a sheet, and preferably 10 μm or more and 500 μm or less in the case of a film.
　上記保護層に用いられる材料に特に制限はないが、ポリエステル樹脂、セルロース樹脂、ビニルアルコール樹脂、ビニル樹脂、シクロオレフィン系樹脂、ポリカーボネート樹脂、アクリル樹脂、ＡＢＳ樹脂等の熱可塑性樹脂、光硬化性樹脂および熱硬化性樹脂などの公知のコーティング材料を用いることができる。保護層の材料は密着性の観点からは基材と同じ材料が好ましく例えば基材がポリエステル樹脂の場合は保護層がポリエステル樹脂であることが好ましい。保護層の膜厚は厚すぎると導電層の接触抵抗が大きくなり、薄すぎると保護層としての効果が得られないので１ｎｍ以上１μｍ以下が好ましく、１０ｎｍ以上１００ｎｍ以下がより好ましい。 Although there is no restriction | limiting in particular in the material used for the said protective layer, Thermoplastic resins, such as a polyester resin, a cellulose resin, a vinyl alcohol resin, a vinyl resin, a cycloolefin resin, a polycarbonate resin, an acrylic resin, an ABS resin, a photocurable resin In addition, a known coating material such as a thermosetting resin can be used. The material of the protective layer is preferably the same material as the base material from the viewpoint of adhesion. For example, when the base material is a polyester resin, the protective layer is preferably a polyester resin. If the thickness of the protective layer is too thick, the contact resistance of the conductive layer increases, and if it is too thin, the effect as the protective layer cannot be obtained, and is preferably 1 nm or more and 1 μm or less, and more preferably 10 nm or more and 100 nm or less.
　本発明はさらに単層カーボンナノチューブ分散液の製法であって、工程１：粗カーボンナノチューブを得る工程、工程２：粗カーボンナノチューブを、酸処理する工程、工程３：工程２で得られた単層カーボンナノチューブをアルカリ処理する工程、工程４：工程３で得られた単層カーボンナノチューブを中空糸膜を用いて濾過する工程、工程５：工程４で得られた単層カーボンナノチューブを酸処理する工程を含むことを特徴とする単層カーボンナノチューブ分散液の製造方法を提供する。 The present invention further relates to a method for producing a single-walled carbon nanotube dispersion, wherein step 1: a step of obtaining a crude carbon nanotube, step 2: a step of acid-treating the crude carbon nanotube, step 3: a single-layer obtained in step 2 Step of alkali-treating carbon nanotubes, Step 4: Step of filtering single-walled carbon nanotubes obtained in Step 3 using a hollow fiber membrane, Step 5: Step of acid-treating single-walled carbon nanotubes obtained in Step 4 A method for producing a single-walled carbon nanotube dispersion liquid is provided.
　上記工程１～５はこの順番で行なうことが好ましい。以下それぞれの工程について説明する。 The above steps 1 to 5 are preferably performed in this order. Each process will be described below.
工程１：粗カーボンナノチューブを得る工程は公知の製法であれば特に制限はなく、アーク放電法、化学気相蒸着法、レーザー蒸発法などいずれの製法も利用することができるが、入手容易性と結晶性の観点からアーク放電法による製造法が最も好ましい。 Step 1: The step of obtaining the crude carbon nanotube is not particularly limited as long as it is a known production method, and any production method such as an arc discharge method, a chemical vapor deposition method, or a laser evaporation method can be used. From the viewpoint of crystallinity, the production method by the arc discharge method is most preferable.
工程２：粗カーボンナノチューブを酸処理する工程は酸性液体中で単層カーボンナノチューブを加熱する方法である。酸性液体は公知の化合物であれば特に制限はなく、具体的には硝酸、塩酸、硫酸、リン酸及びこれらの混合物が挙げられる。
　本発明においてアルカリ処理前の酸処理は硝酸あるいは硝酸と硫酸の混合液を用いた酸処理が好ましく、８０℃以上１００℃以下で反応させることがより好ましく、１日以上７日間以下反応させることがより好ましい。 Step 2: The step of acid-treating the crude carbon nanotube is a method of heating the single-walled carbon nanotube in an acidic liquid. The acidic liquid is not particularly limited as long as it is a known compound, and specific examples include nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, and mixtures thereof.
In the present invention, the acid treatment prior to the alkali treatment is preferably acid treatment using nitric acid or a mixed solution of nitric acid and sulfuric acid, more preferably 80 to 100 ° C., more preferably 1 to 7 days. More preferred.
工程３：工程２で得られた単層カーボンナノチューブをアルカリ処理する工程は、単層カーボンナノチューブをアルカリ性液体中に浸漬させる方法である。アルカリ性液体は公知のものであれば特に制限はなく具体的には水酸化リチウム水溶液、水酸化ナトリウム水溶液、水酸化カリウム水溶液、アンモニア水溶液、プロピルアミン、ブチルアミンなどのアルキルアミン水溶液などが挙げられる。
　本発明においてアルカリ処理時に用いるアルカリ性液体は水酸化リチウム水溶液、水酸化ナトリウム水溶液、水酸化カリウム水溶液が好ましく、水酸化ナトリウム水溶液がより好ましい。 Step 3: The step of alkali-treating the single-walled carbon nanotubes obtained in Step 2 is a method of immersing the single-walled carbon nanotubes in an alkaline liquid. The alkaline liquid is not particularly limited as long as it is a known one, and specific examples include an aqueous lithium hydroxide solution, an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution, an aqueous ammonia solution, and an alkylamine aqueous solution such as propylamine and butylamine.
In the present invention, the alkaline liquid used during the alkali treatment is preferably a lithium hydroxide aqueous solution, a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution, more preferably a sodium hydroxide aqueous solution.
工程４：工程３で得られた単層カーボンナノチューブを、ろ過する工程は炭素粒子などの不純物を除去する工程である。酸処理を行なったカーボンナノチューブの反応液は直径２０ｎｍ程度の不純物の粒子とカーボンナノチューブのバンドルとが分離された状態で溶液中に分散あるいは沈殿している。このため、不純物よりも大きく、かつカーボンナノチューブのバンドルよりも小さい孔径のフィルターを用いてろ過することによって不純物を取り除くことができる。
　ろ過方法としては公知のろ過方法であれば制限はなく、吸引ろ過や加圧ろ過、クロスフローろ過などを用いることができる。中でもスケールアップの観点からは中空糸膜を用いたクロスフローろ過がより好ましい。 Step 4: The step of filtering the single-walled carbon nanotubes obtained in Step 3 is a step of removing impurities such as carbon particles. The reaction solution of carbon nanotubes subjected to the acid treatment is dispersed or precipitated in the solution in a state in which impurity particles having a diameter of about 20 nm and carbon nanotube bundles are separated. For this reason, the impurities can be removed by filtering using a filter having a pore size larger than the impurities and smaller than the bundle of carbon nanotubes.
The filtration method is not particularly limited as long as it is a known filtration method, and suction filtration, pressure filtration, crossflow filtration, or the like can be used. Among these, from the viewpoint of scale-up, cross flow filtration using a hollow fiber membrane is more preferable.
工程５：工程４で得られた単層カーボンナノチューブを酸処理する工程は、酸性液体中に単層カーボンナノチューブを浸漬する方法である。酸性液体は公知の化合物であれば特に制限はなく、具体的には硝酸、塩酸、硫酸、リン酸及びこれらの混合物が挙げられる。なかでも塩酸がより好ましい。さらに室温状態で行なうことがより好ましい。 Step 5: The step of acid-treating the single-walled carbon nanotubes obtained in Step 4 is a method of immersing the single-walled carbon nanotubes in an acidic liquid. The acidic liquid is not particularly limited as long as it is a known compound, and specific examples include nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, and mixtures thereof. Of these, hydrochloric acid is more preferable. Furthermore, it is more preferable to carry out at room temperature.
　本発明の単層カーボンナノチューブ分散液の製造方法は上記工程１～５を含むものであれば特に制限はないが、例えば工程５の後に工程５で得られた単層カーボンナノチューブとフラーレンまたはその類縁体を混合し超音波を照射する工程を行なうことも可能である。
　単層カーボンナノチューブとフラーレンとの割合には特に制限はないが、単層カーボンナノチューブ１００質量部に対してフラーレンが、１０～１０００質量部であることが好ましい。そして、フラーレン濃度は、１～１０００００ｐｐｍであることが好ましい。フラーレンは、特に、ＯＨ基を有するフラーレンが好ましい。 The method for producing a single-walled carbon nanotube dispersion of the present invention is not particularly limited as long as it includes the above-mentioned steps 1 to 5, but for example, the single-walled carbon nanotube obtained in step 5 after step 5 and fullerene or the like. It is also possible to mix the body and irradiate with ultrasonic waves.
The ratio of the single-walled carbon nanotube and fullerene is not particularly limited, but the fullerene is preferably 10 to 1000 parts by weight with respect to 100 parts by weight of the single-walled carbon nanotube. The fullerene concentration is preferably 1 to 100,000 ppm. The fullerene is particularly preferably a fullerene having an OH group.
　超音波を照射する方法としては公知の方法であれば特に制限は無く、バス型超音波照射機やチップ型超音波照射機を用いることが可能であり、より短時間で処理する観点からはチップ型超音波照射機を用いることがより好ましい。 As a method for irradiating ultrasonic waves, there is no particular limitation as long as it is a known method, and it is possible to use a bath type ultrasonic irradiator or a chip type ultrasonic irradiator. From the viewpoint of processing in a shorter time, a chip. It is more preferable to use a type ultrasonic irradiator.
　本発明で用いられる溶媒は、一般の塗料で用いられる溶媒であれば制限は無い。但し、沸点が２００℃以下（好ましい下限値は２５℃、更には３０℃）の溶媒が好ましい。低沸点溶剤が好ましいのは、塗工後の乾燥が容易であるからによる。具体的には、水や、メタノール、エタノール、ノルマルプロパノール、イソプロパノールなどのアルコール化合物（特に、炭素数が７以下のアルコール、特に脂肪族アルコール）、或いはこれ等の混合物が好ましい。それは、水酸基含有フラーレンの溶解性が高いので、より高濃度の単層カーボンナノチューブ分散液が得られるからである。他にも、例えばアセトン、メチルエチルケトン、メチルイソブチルケトン、シクロヘキサノン等のケトン系化合物、酢酸メチル、酢酸エチル、酢酸ブチル、乳酸エチル、酢酸メトキシエチルなどのエステル系化合物、ジエチルエーテル、エチレングリコールジメチルエーテル、エチルセロソルブ、ブチルセロソルブ、フェニルセロソルブ、ジオキサン等のエーテル系化合物、トルエン、キシレンなどの芳香族化合物、ペンタン、ヘキサンなどの脂肪族化合物、塩化メチレン、クロロベンゼン、クロロホルムなどのハロゲン系炭化水素、及びこれらの混合物を用いることもできる。 The solvent used in the present invention is not limited as long as it is a solvent used in general paints. However, a solvent having a boiling point of 200 ° C. or lower (preferably lower limit is 25 ° C., further 30 ° C.) is preferable. The low boiling point solvent is preferred because it is easy to dry after coating. Specifically, water, alcohol compounds such as methanol, ethanol, normal propanol, and isopropanol (particularly alcohols having 7 or less carbon atoms, particularly aliphatic alcohols), or a mixture thereof are preferable. This is because the hydroxyl group-containing fullerene has a high solubility, so that a single-walled carbon nanotube dispersion with a higher concentration can be obtained. In addition, for example, ketone compounds such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, ester compounds such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, methoxyethyl acetate, diethyl ether, ethylene glycol dimethyl ether, ethyl cellosolve , Ether compounds such as butyl cellosolve, phenyl cellosolve and dioxane, aromatic compounds such as toluene and xylene, aliphatic compounds such as pentane and hexane, halogenated hydrocarbons such as methylene chloride, chlorobenzene and chloroform, and mixtures thereof You can also
　上記製造方法によって得られた分散液を基板上に塗布することで導電膜を製造することができる。
　具体的には分散液を基材上にスプレーコート、バーコート、ロールコート、インクジェット法、スクリーンコート等の公知の塗布方法を用いて製膜する方法が挙げられる。
　さらに必要に応じて上記塗布工程後、塗膜中に含まれる溶媒を除去する為、乾燥が行なわれる。用いられる乾燥装置としては、例えば通常乾燥に使用される加熱炉、遠赤外炉、超遠赤外炉などを用いることができる。 A conductive film can be manufactured by apply | coating the dispersion liquid obtained by the said manufacturing method on a board | substrate.
Specifically, there is a method of forming a film of the dispersion liquid on a substrate using a known coating method such as spray coating, bar coating, roll coating, ink jet method, screen coating or the like.
Further, after the coating step, if necessary, drying is performed to remove the solvent contained in the coating film. As a drying apparatus used, for example, a heating furnace, a far-infrared furnace, a super far-infrared furnace, etc. that are usually used for drying can be used.
　一方、上記の工程４までで得られた単層カーボンナノチューブ分散液を上記した方法で基板上に塗布し、得られた導電層を酸処理することによっても本発明の導電膜を製造することができる。
　具体的には、上記導電層に酸性液体を噴霧、塗布する方法や、該導電層を酸性液体に浸漬する方法等が挙げられる。酸性液体は公知の化合物であれば特に制限はなく、具体的には硝酸、塩酸、硫酸、リン酸及びこれらの混合物が挙げられる。なかでも塩酸がより好ましい。さらに室温状態で行なうことがより好ましい。また、上記導電層をメタノール等のアルコール類または純水などで洗浄し、残留している酸性液体を除去することも可能である。 On the other hand, the conductive film of the present invention can also be produced by applying the single-walled carbon nanotube dispersion liquid obtained up to step 4 on the substrate by the above-described method and acid-treating the obtained conductive layer. it can.
Specific examples include a method of spraying and applying an acidic liquid to the conductive layer, a method of immersing the conductive layer in an acidic liquid, and the like. The acidic liquid is not particularly limited as long as it is a known compound, and specific examples include nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, and mixtures thereof. Of these, hydrochloric acid is more preferable. Furthermore, it is more preferable to carry out at room temperature. It is also possible to remove the remaining acidic liquid by washing the conductive layer with alcohols such as methanol or pure water.
　上記のようにして導電膜が得られる。具体的には、全光線透過率が６０％以上で、かつ、表面抵抗値が１００００Ω／□以下の透明な導電膜が得られる。更には全光線透過率が７０％以上で、かつ、表面抵抗値が３０００Ω／□以下の透明な導電膜が簡単・低コストで得られる。なお、ここで、全光線透過率は単層カーボンナノチューブを含む導電膜のみならず基材を含めた全光線透過率である。そして、上記した特長の導電膜は、タッチパネル用電極基板、電子ペーパーの電極基板、液晶ディスプレイの電極基板、プラズマディスプレイの電極基板などに利用できる。 A conductive film is obtained as described above. Specifically, a transparent conductive film having a total light transmittance of 60% or more and a surface resistance value of 10,000 Ω / □ or less is obtained. Furthermore, a transparent conductive film having a total light transmittance of 70% or more and a surface resistance value of 3000Ω / □ or less can be obtained easily and at low cost. Here, the total light transmittance is the total light transmittance including not only the conductive film containing single-walled carbon nanotubes but also the substrate. The conductive film having the features described above can be used for an electrode substrate for a touch panel, an electrode substrate for electronic paper, an electrode substrate for a liquid crystal display, an electrode substrate for a plasma display, and the like.
＜実施例１＞
　５Ｌセパラブルフラスコにアーク放電法によって得られた粗単層カーボンナノチューブ３０ｇ、蒸留水３００ｍｌを投入し、粗単層カーボンナノチューブを完全に蒸留水にて湿潤させた。
　メカニカルスターラーにて攪拌しつつ、６９％硝酸（和光純薬工業社製）２７００ｍｌを滴下した後、８５℃にて４８時間攪拌した。
　反応液を室温まで冷却後、遠心分離機（製品名ＣＲ２６Ｈ　日立工機株式会社製）により固体分を回収し、水酸化ナトリウム水溶液（ｐＨ１０）６０００ｍｌに投入した。
さらにポリエチレングリコールモノオクチルフェニルエーテル（東京化成社製）を０．５ｗｔ％になるように添加して、コーン型超音波照射機（装置名ＵＬＴＲＡＳＯＮＩＣ　ＨＯＭＯＧＥＮＩＺＥＲ　ＭＯＤＥＬ　ＵＨ－６００ＳＲ、エスエムテー社製）にて超音波を５分間照射した。
　反応液を、遠心分離機を用いて１３０００ｒｐｍにて１時間遠心分離を行ない、上澄み液を回収して粗精製液とした。 <Example 1>
A 5 L separable flask was charged with 30 g of crude single-walled carbon nanotubes obtained by an arc discharge method and 300 ml of distilled water, and the crude single-walled carbon nanotubes were completely wetted with distilled water.
While stirring with a mechanical stirrer, 2700 ml of 69% nitric acid (manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise, followed by stirring at 85 ° C. for 48 hours.
After the reaction solution was cooled to room temperature, the solid content was recovered by a centrifuge (product name: CR26H, manufactured by Hitachi Koki Co., Ltd.) and put into 6000 ml of an aqueous sodium hydroxide solution (pH 10).
Furthermore, polyethylene glycol monooctylphenyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) was added so as to be 0.5 wt%, and ultrasonic waves were applied using a cone type ultrasonic irradiator (device name: ULTRASONIC HOMOGENIZER MODEL UH-600SR, manufactured by SMT Corporation). Was irradiated for 5 minutes.
The reaction solution was centrifuged at 13000 rpm for 1 hour using a centrifuge, and the supernatant was recovered to obtain a crude purified solution.
　粗精製液を、クロスフローろ過に供した。使用した中空糸膜モジュールは孔径２００ｎｍ、膜面積５８００ｃｍ２（ＳＰＥＣＴＲＵＭ社製）であり、洗浄液は０．００５Ｍ水酸化ナトリウム水溶液に０．２ｗｔ％になるようにポリエチレングリコールモノオクチルフェニルエーテルを加えた弱アルカリ性水溶液である。粗精製液を１２０．０Ｌの洗浄液で洗浄することによって、６０００ｍｌの精製単層カーボンナノチューブの分散液を得た。
　得られた分散液をポリカーボネート板上にスプレーコートした。
　さらにメタノールで塗工面を洗浄後８０℃で３分間乾燥させた。
　さらに０．１Ｍ塩酸溶液に１分間浸漬しメタノールで塗工面を洗浄後８０℃で３分間乾燥させることによって導電層付ポリカーボネート板を得た。 The crude purified solution was subjected to cross flow filtration. The hollow fiber membrane module used has a pore size of 200 nm and a membrane area of 5800 cm 2 (manufactured by SPECTRUM). Alkaline aqueous solution. The crude purified solution was washed with 120.0 L of washing solution to obtain 6000 ml of a purified single-walled carbon nanotube dispersion.
The obtained dispersion was spray coated on a polycarbonate plate.
Further, the coated surface was washed with methanol and dried at 80 ° C. for 3 minutes.
Further, it was immersed in a 0.1 M hydrochloric acid solution for 1 minute, washed with methanol and then dried at 80 ° C. for 3 minutes to obtain a polycarbonate plate with a conductive layer.
＜実施例２＞
　実施例１で得られた精製単層カーボンナノチューブの分散液１００ｍｌに１Ｍ塩酸をｐＨ４になるまで加え中和した後、イソプロピルアルコール１００ｍｌを加え、遠心分離機にて単層カーボンナノチューブを固体状態で回収した。
　得られた単層カーボンナノチューブと、水酸基含有フラーレン（商品名　ナノムスペクトラ　Ｄ－１００　フロンティアカーボン社製：Ｃ６０フラーレン）１０ｍｇと、水酸化ナトリウム（和光純薬工業社製）１ｍｇと、水５０ｍｌと、イソプロピルアルコール５０ｍｌとを混合し、超音波装置（ＵＬＴＲＡＳＯＮＩＣ　ＨＯＭＯＧＥＮＩＺＥＲ　ＭＯＤＥＬ　ＵＨ－６００ＳＲ、エスエムテー社製）を用いて、混合液に超音波を１分間に亘って照射し、超音波分散を行ない、単層カーボンナノチューブ分散液を得た。 <Example 2>
After neutralizing 1M hydrochloric acid to pH 4 to 100 ml of the purified single-walled carbon nanotube dispersion obtained in Example 1, 100 ml of isopropyl alcohol was added, and the single-walled carbon nanotubes were recovered in a solid state with a centrifuge. did.
The obtained single-walled carbon nanotube, 10 mg of hydroxyl group-containing fullerene (trade name: Nanomuspectra D-100 Frontier Carbon Co., Ltd .: C60 fullerene), 1 mg of sodium hydroxide (Wako Pure Chemical Industries, Ltd.), 50 ml of water, isopropyl Single-walled carbon nanotubes are mixed with 50 ml of alcohol and irradiated with ultrasonic waves for 1 minute using an ultrasonic device (ULTRASONIC HOMOGENIZER MODEL UH-600SR, manufactured by SMT Co., Ltd.). A dispersion was obtained.
　得られた単層カーボンナノチューブ分散液をハードコート付ポリカーボネート基板上にバーコート法により塗布した。その厚さはウェット膜厚で５０μｍである。
　この後、８０℃で３分間乾燥させ、メタノールで表面を洗浄した。
　さらに８０℃で３分間乾燥させ、導電層付ポリカーボネート板を得た。 The obtained single-walled carbon nanotube dispersion was applied to a hard-coated polycarbonate substrate by a bar coating method. The thickness is 50 μm in wet film thickness.
Then, it was dried at 80 ° C. for 3 minutes, and the surface was washed with methanol.
Furthermore, it was dried at 80 ° C. for 3 minutes to obtain a polycarbonate plate with a conductive layer.
＜実施例３＞
　実施例２で得られた導電層付ポリカーボネート板上に、保護層としてアクリル樹脂（商品名　ＷＡＴＡＲＳＯＬ　Ｓ－７０７ＩＭ　大日本インキ化学工業株式会社製）積層した。具体的には該アクリル樹脂を１質量％のイソプロピルアルコール溶液としディップコートした後８０℃で３分間乾燥した。 <Example 3>
On the polycarbonate plate with a conductive layer obtained in Example 2, an acrylic resin (trade name: WATERSOL S-707IM, manufactured by Dainippon Ink & Chemicals, Inc.) was laminated as a protective layer. Specifically, the acrylic resin was dip-coated as a 1% by mass isopropyl alcohol solution and then dried at 80 ° C. for 3 minutes.
＜比較例１＞
　実施例１で得られた精製単層カーボンナノチューブの分散液をポリカーボネート板上にスプレーコートした。
　さらにメタノールで塗工面を洗浄後８０℃で３分間乾燥させ導電層付ポリカーボネート板を得た。
　さらに保護層としてアクリル樹脂（商品名　ＷＡＴＡＲＳＯＬ　Ｓ－７０７ＩＭ　大日本インキ化学工業株式会社製）積層した。具体的には該アクリル樹脂を１質量％のイソプロピルアルコール溶液としディップコートした後８０℃で３分間乾燥した。 <Comparative Example 1>
The dispersion of purified single-walled carbon nanotubes obtained in Example 1 was spray coated on a polycarbonate plate.
Further, the coated surface was washed with methanol and dried at 80 ° C. for 3 minutes to obtain a polycarbonate plate with a conductive layer.
Further, an acrylic resin (trade name: WATERSOL S-707IM, manufactured by Dainippon Ink & Chemicals, Inc.) was laminated as a protective layer. Specifically, the acrylic resin was dip-coated as a 1% by mass isopropyl alcohol solution and then dried at 80 ° C. for 3 minutes.
［特性］
　得られた導電層付ポリカーボネート板の全光線透過率（装置名　直読ヘーズコンピュータ、スガ試験機社製）と表面抵抗値（装置名　ロレスタ－ＥＰ、ダイアインスツルメンツ社製）とを測定したので、その結果を表１に記す。また、８０℃で１０日間保存した後、表面抵抗値を測定したので、その結果も併せて表１に示す。 [Characteristic]
The total light transmittance (device name direct reading haze computer, manufactured by Suga Test Instruments Co., Ltd.) and surface resistance value (device name: Loresta EP, manufactured by Dia Instruments Co., Ltd.) of the obtained polycarbonate plate with conductive layer were measured. Is shown in Table 1. In addition, since the surface resistance value was measured after storage at 80 ° C. for 10 days, the results are also shown in Table 1.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　これによれば、本発明の導電膜は、透光性に優れていることが判る。その上で、導電性にも優れており、かつ、その高温時における劣化が低く、耐久性に優れていることが判る。 According to this, it turns out that the electrically conductive film of this invention is excellent in translucency. In addition, it can be seen that it is excellent in conductivity, has low deterioration at high temperatures, and is excellent in durability.

Claims (7)

  1. 　単層カーボンナノチューブを含む導電膜であって、該単層カーボンナノチューブが酸処理後アルカリ処理され、さらに酸処理されて得られるものであることを特徴とする導電膜。 A conductive film comprising single-walled carbon nanotubes, wherein the single-walled carbon nanotubes are obtained by acid treatment, alkali treatment, and further acid treatment.
  2. 　単層カーボンナノチューブが酸処理後アルカリ処理され、ろ過後に酸処理したものであることを特徴とする請求項１記載の導電膜。 2. The electrically conductive film according to claim 1, wherein the single-walled carbon nanotube is an acid-treated, alkali-treated, and an acid-treated after filtration.
  3. 　フラーレンまたはその類縁体を含むことを特徴とする請求項１または２記載の導電膜。 The conductive film according to claim 1, comprising fullerene or an analog thereof.
  4. 　基板上に請求項１～３いずれか１項に記載の導電膜と保護層を有することを特徴とする電極。 An electrode comprising the conductive film according to any one of claims 1 to 3 and a protective layer on a substrate.
  5. 　単層カーボンナノチューブ分散液の製造方法であって、
    工程１：粗カーボンナノチューブを得る工程；
    工程２：粗カーボンナノチューブを酸処理する工程；
    工程３：工程２で得られた単層カーボンナノチューブをアルカリ処理する工程；
    工程４：工程３で得られた単層カーボンナノチューブをろ過する工程；
    工程５：工程４で得られた単層カーボンナノチューブを酸処理する工程；
    を含むことを特徴とする単層カーボンナノチューブ分散液の製造方法。     A method for producing a single-walled carbon nanotube dispersion,
    Step 1: obtaining crude carbon nanotubes;
    Step 2: acid treating the crude carbon nanotube;
    Step 3: A step of alkali-treating the single-walled carbon nanotubes obtained in Step 2;
    Step 4: Filtering the single-walled carbon nanotubes obtained in Step 3;
    Step 5: A step of acid-treating the single-walled carbon nanotubes obtained in Step 4;
    The manufacturing method of the single-walled carbon nanotube dispersion liquid characterized by including this.
  6. 　請求項５記載の単層カーボンナノチューブ分散液の製造方法によって得られた分散液を基板上に塗布する工程を有することを特徴とする導電膜の製造方法。 A method for producing a conductive film, comprising a step of applying a dispersion obtained by the method for producing a single-walled carbon nanotube dispersion according to claim 5 on a substrate.
  7. 　単層カーボンナノチューブを含む導電膜の製造方法であって、
    工程１：粗カーボンナノチューブを得る工程；
    工程２：粗カーボンナノチューブを酸処理する工程；
    工程３：工程２で得られた単層カーボンナノチューブをアルカリ処理する工程；および
    工程４：工程３で得られた単層カーボンナノチューブをろ過する工程；
    を含む単層カーボンナノチューブを含む分散液を得る工程Ａ；
    工程Ａで得られた単層カーボンナノチューブを基板上に塗工して導電層を得る工程Ｂ；並びに、
    工程Ｂで得られた導電層を酸処理する工程Ｃ；
    を含むことを特徴とする単層カーボンナノチューブ含む導電膜の製造方法。     A method for producing a conductive film comprising single-walled carbon nanotubes,
    Step 1: obtaining crude carbon nanotubes;
    Step 2: acid treating the crude carbon nanotube;
    Step 3: a step of alkali-treating the single-walled carbon nanotubes obtained in Step 2; and Step 4: a step of filtering the single-walled carbon nanotubes obtained in Step 3;
    Step A for obtaining a dispersion containing single-walled carbon nanotubes containing
    Applying the single-walled carbon nanotubes obtained in step A onto a substrate to obtain a conductive layer;
    Step C of acid-treating the conductive layer obtained in Step B;
    A process for producing a conductive film containing single-walled carbon nanotubes, comprising:
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